Process for obtaining gases rich in ethylene



Patented Aug. 27, 1929. I

UNITED STATES PATENT OFFICE.

HERMANN SUIDA, OF MODLING,fAUSTBIA, ASSIGNOR TO I. G. FARBENINDUSTRIE AK- '.I.IENGESELLSOHAFT, OF ERANKFORT-ON-TEE-MAIN, GERMANY, A. CORPORATION or GERMANY.

PROCESS FOR OBTAINING GASES RICH IN ETHYLENE.

No Drawing. Application filed June 24, 1924, Serial No. 722,132, and in Austria .Tune 26, 1923.

It is known that by destructive distillation of tar-oils and of certain fractions of mineral oils gases containing olefines ma be obtained. This process has been used or a long time and on a large scale for the manufacture 'of oil gas. As a rule these gases, however, contain not more than 20% of olefines. Furthermore -the olefines only partly consist of ethylene and besides c0ntain considerable quantities of higher olefines wherebythevalue of the gases is substantially impaired for some purposes since the component of high commercial value is ethylene.- The statements given in the textbooks and other publications of the art are not correct as the olefinesare inmost cases.

not, specified but indicated as an entirety, the total mixture being sometimes desig nated as ethylene no separation of the olefines by analysis having occurred. Upon examination it may, however, be shown that v the temperatures which yield a high peroentage of mixed olefines {GOO-700 G.) are those, at whichthe higher homologues pre- 2 Vail. At highertemperatu res the production of olefines 'is reduced in favor of methane.

and hydrogen, though therfiain constituent of the olefine mixture is then ethylene.

-- I have made the surprising discovery, that it is possible to obtain at high temperatures gases rich in olefines and particularly in ethylene if oare'betaken to avoid a destruction of-the ethylene or' ce formed. This ad-' 10 to of'olefines nearly exclusively con sisting of ethylene. It is a surprising fact that by the use of steam at 800 to -900 C.

' not only the formation of ethylene is "improved but alsothe output of olefines calculated on the quantity of tar oil used as steam, gases of a much lowerleontent of ole fines 'are'obtained. .The destructive distillastarting, material is considerably raised. Under *equal conditions but in absence of tion of tar oils, mineral oils and resinous oils in the presence'of steam, has been described in British Patent No. 19,096/1895 and in German Patent No. 36,134.- AQ D. 1886. 'The Y processes described in these. patents were, however, carried out to serve other purposes, namely to obtain oils of low boiling point and as to the manufacture of heating gases, no particulars as regards the temperature were disclosed in said patents.

The above described behavior of the tar oils at the indicated. temperatures could not be foreseen since olefines practically can not be obtained at such high temperatures and it was not likely that the presence of watei vapor' would thus modify the cracking process apart from lowering the temperature of distillation which however, does not occur inxthis case. As regards the improvement of the output of olefines a process by which'water-gas is simultaneously produced owing to the presence of steam and carbon produced by destruction is out ofthe'question, since by such process only hydrogen and carbonmonoxide but no olefines could" be produced and by combination of the hydrogen with the olefines their output could only be reduced and-not raised,

Emample.

When oil, for instance such oilas will be obtained by simple distillation of brown coal generator tar and. having a boiling point of 300 to 350 C. are introduced in a crude state intoan iron tube of 900 C. with an equal quantity; of steam, considerable quantities by weight of a gas containing 44 to 48% ethylene will be obtained besides liquid jdistillates. "amounts to about 300 to 400 liters for each The. total gas output kilogram of oil. On using more or less steam the output will be reduced. It is therefore most advantageous to use equal uantities of oil and steam. If the distillation be carried out in the absence of steam I but with otherwise similar conditions a gas with" 30% of olefines is obtained.

Instead of brown coal tar oils,I may use as well black coal tar oil obtained by dis tillation at low temperatures or fractions of said oil, which are more advantageous than the ordinary mineral oil fractions in that the gases do not contain heavy saturated hydrocarbons besides the olefines, whereas fractions of mineral oils, such as gas oil 1 upon cracking Will always yield large quantities of ethane which cannot be separated 5 from the ethylene Without diiiiculty.

The gases obtained by the process according to my invention may easily be Worked down to concentrated ethylene gas in a known manner for instance by concentrating the ethylene by means of active charcoal; by a single-passage of the gas over charcoal a 80 to 90% ethylene may be obtained.

This is impossible with gases obtained by cracking mineral oils which are rich in olefines but inwhich the concentration of ethylene is hindered by the presence of ethane.

It is to be understood that the concentration of the crude gas may as well be cars ried out by partial liquefaction and distillation.

What I claim is: 1. A process for obtaining gases rich in ethylene which consists in subjecting tar 2 oils of a high boiling point to destructive by Weight of steam being approximatelyihe same as that of the tar oil,

4. A process for obtaining gases rich in 40 ethylene which consists in subjecting lignite tar oils of a high boiling point to destructive distillation in the presence of steam and at temperatures of 800 to 900 0., the the quantity by Weight of steam being approximately the same as that of the tar oil.

In testimony whereof I have hereunto set my hand.

HERMANN SUIDA.

CERTIFICATE or connection.

Patent No. l, 7 26, 04$.

Granted August 27, 1929, to

HERMANN SUIDA.

It is hereby certified. that "error appears in the printed specification of the above numbered patent requiring correction asfollows: word "or!" both occurrences, read "oils"; I

be read with this correction therein that the case in the Patent Office.

Page 1, line 84, forthe and that the said Letters Patent should the same may conform to the record of Signed and sealed this 1st day of October, A. D. 1929.

M; J. Moore, Acting Commissioner of Patents. 

